Surgical and anatomical details of the breast

The 3-step principle

The 3-step principle of breast analysis was developed to help describe and deal with complex deformities of the female breast. It divides the breast into 3 simple anatomical features; the footprint, the conus and the skin envelope.

(1) The footprint

The footprint is the outline of the breast base on the chest wall and is the interface of the posterior surface of the breast with the thoracic cavity. The footprint forms the foundation of the overlying three-dimensional structure of the breast (fig. 1).

The footprint can easily be seen at the end of a mastectomy, if the overlying skin is retracted, exposing the serratus anterior and pectoral muscles.

Fig. 1

Fig. 1: Typical size and position of the breast footprint on the chest wall on a frontal (a) sagittal standing (b) and an axial supine view (c).

(2) The conus

The conus refers to the three dimensional shape, projection and volume of the breast. It is normally formed by the mammary gland and sits anterior to the footprint of the breast (fig. 2).

Each conus has a specific volume and yet its composition is different in every individual woman. The base of the conus corresponds to, or is slightly smaller than, the breast footprint.

In a standing position, there is a gradual transition of the chest wall into the upper and medial aspects of the female breast. The infraclavicular area is typically flat or even slightly concave.

This transition at the lateral and inferior part of a normal breast is sharper and may even reach 180° at the lower border of hypertrophic or severely ptotic breasts.

The conus typically has lower lateral fullness, a maximum projection at the level of the nipple-areolar complex just lateral to the mid-clavicular line and a varying degree of ptosis.

Fig. 2

Fig. 2: Typical size and position of the footprint (blue) and the conus (yellow) of the breast on the chest wall in a frontal (a) sagittal standing (b) and an axial supine view (c).

(3) The skin envelope

The skin envelope is the overlying skin and subcutaneous fat of the breast (fig. 3). Normally the skin envelope functions like a well-fitting brassiere, holding the conus in position and aiding projection.

The interface between the skin envelope and the conus can play an important role in breast shape. Scarring, due to surgery or radiotherapy, can tighten the envelope, while stretching of Cooper’s ligament or the superficial layer of the superficial fascia can loosen this envelope.

Fig. 3

Fig. 3: Typical size and position of the footprint (blue), the conus (yellow) and the skin envelope (orange) of the breast on the chest wall in a frontal (a) sagittal standing (b) and an axial supine view (c).

The nipple-areolar complex (NAC) is also a component of the skin envelope. It contributes to the overall aesthetic appearance of the breast, by highlighting the point of maximal anterior-posterior projection, along either the vertical meridian line or slightly lateral to it (fig. 4).

An attractive areola is pigmented, has a conical shape and is a smooth continuation of the natural contour of the skin envelope of the breast. The nipple protrudes above the areola.

Fig. 4: The nipple-areolar complex (NAC) sits at the point of maximal anterior-posterior projection of the breast, either along the vertical meridian line or just slightly lateral to it.

The final breast shape is not determined independently by the footprint, the conus or the skin envelope. It is the interaction of these 3 elements that contributes to the maintenance of a pleasing, natural-looking breast over time.

References

Shaping the breast in aesthetic and reconstructive breast surgery: an easy three-step principle.